red hot glowing cat, funky o2 wiring, and more b16 fun, kinda long beware...

Thanks to all reading this, I hope it helps someone else too.
so started my car with b16 swap and my cat was GLOWING RED HOT. Like HOT LAVA type hot, i thought my car was going to burn I was so scared!
Well that’s bad but not unfixable. I believe it’s a problem with my timing, which I have not done yet? My exhaust was always fine before, and it starts and i see smoke coming out the back so I assume that it wont be clogged. I will hollow it out just to be safe after i do my timing, which i plan to do tonight if anyone answers quickly enough. (If that is not the problem I am going to use my b18 dizzy and cut the leg off)

During the swap I was forced to take the crank pulley off and swap it for my b18 one. Does that mean the hash marks are gone or off of TDC? Or are they on the other disk closer in. (I don’t remember if that came off)

Secondly the second oxygen sensor needs to be wired. I just jumped c8 and c16 but the guy at the tuner shop said no i need to do it with the wires instead (somehow). Does anyone know what he means or why this would make a difference? im running an ls harness so it doesn’t have the other oxygen sensor.

Also wondering, of the two wires in the vtec oil pressure, which one is the ground. I don’t have the harness and im using the ls harness so it’s not there. I just guessed.

Thanks a lot u guys for your prompt and always helpful answers!

:mad: :argh:
ok so i did the timing and fixed that and oh yeah i changed the wiring order, two of them were wrong!! I can’t believe it ran that well with the spark plugs wrong. Then I took it to the gas station to fill it up because i had previously hooked the fuel return line to the coolant and wanted to dilute the gas:coolant ratio. It was fine just about up until 4000 rpm, where it lost power. I didn’t press the accelerator too hard until just before my driveway and i think i could hear the vtec.
Im throwing a code 5, which i think is map sensor. I messed with it, stopped throwing the code, but I noticed that the cat heated up again and started glowing RED HOT again.

45 views and nobody has an idea? bump

46 views and still no one can figure out what the hell you’re trying to say.

yeah, everyone has an idea:


don’t know how many times that needs to be said.

apparently you have NO CLUE on how to fix/diagnose problems, and yet you continue to drive the car in the messed up state it is in. You fiddle with problems that you think you have knowledge of, but don’t, when in reality are messing things up. you should leave it to a competent shop to handle.

sheesh :roll: :bang:

at this point, radzer0 is more competent to fix things than you are.


still tying to figure out what the obsession with “tuner shops” is. There are a few out here <cough cough> Intercrew <cough cough> JoTech (aka Joketech) <cough> <cough> that have had rave reviews for fucking you in the ass with no lube. Take the car to a dealership. Better yet get full coverage insurance and do the old “bick-on-the-gas-pedal-driving-off-a-cliff” attack.

I have the same problem … my cat gets red hot …I let it warm up and I drove around the block and the cat was glowing red hot …

I never change the pulleys or cam gears …

My car also runs like shit it feels like it has no power …it idles bad and it smells like gas is coming out of the tailpipe …

I need help whats up guys


I just swapped in my B20 and I had the same problem, I timed it already, anyone have any ideas?

same probs…

I just did a full rebuild on my b18 and I’m having the same prob with the cat…one exhaust shop said that it was because the old cats aren’t compatible with the new E85 ethanol gas most places are using now…my exhaust was in pretty bad shape, so I had them bend me a new one, replacing everything including the catalytic converter back. 600 dollars later, on the drive back from the shop, my cat still glowed red. Now, something I forgot to mention was that the machine shop that did all of the work on my block fudged something up with the rings, so I’m only getting 95psi for compression across the board (did a wet comp test and it jumped into the 120s, so I know it’s the rings…) so the car runs like crap…I’ve redone the timing 3 times, and all is lined up, but I guess I need to do it again, seeing as 120psi is still not an acceptable compression rating, even with oil in the cylinder. On a side note, has anyone bored their engine .020 over out there that can give me some insight into how the timing may or may not have changed? I’ve spent probably 20 man-hours on g2ic and hondaswap searching for info, but no love.

I went back to the basics, I recehcked the plugs were right the cap, rotor, wires, and finally that I had all of the plugs plugged into the right position. Sure enough I had the firing order wrong ( WOW I FEEL DUMB BTW) anyways it is 1-3-4-2 and I had 1-3-2-4. so check that maybe it is the cause of your problems.



a little searching would explain the catalytic converter business.

I don’t even know how it would be possible to hook up the fuel return line to a coolant connection. They aren’t even close to one another.

Sounds like its time to take the car to someone who knows what they’re doing.

91GSTEG: I have seen many cats HOT. NOthing like what i saw with that firing order wrong It looked like lava red hot, and smoke everyhwere. Alll I did was change the firing order and it doesnt get that bad not even red.

no offense to you guys saying take it to a shop, but some of us don’t have that luxury and what i mean is that there are no competent shops in my area that could handle my motor. I did all the research on my b16 swap myself, told my mechanic(old neighbor) exactly what needed to be done, exactly what parts to use, and what the order the vtec wires were supposed to be in on the ecu. It takes time and research guys!! Do it urself, don’t rely on others, so u get it done right the first time. Don’t ask me how many times i had brought my car to the shop and left with something else wrong. I have to literally watch them do all the work to make sure they aren’t fucking with it, when i got my alignment 1 month ago the guys ripped a hole in my exhaust and i had to bring it back and have it patched.


First of all you should be using the b16a ecu (pw0 or pr3) to begin with because it has 2 slots for the o2 sensors. There is an ecu pinout on this main page that should be able to help u. About the LS harness, i don’t really know anybody that has gotten a useable b16 harness from when they bought there swap cuz they basically cut it right off when taking the motor out. I don’t know what the fuck is going on with u putting gas in ur coolant or w/e but that sounds fucked up altogether. As for the vtec wires there is 1 for the solenoid, 1 for the pressure, 1 for the ground, and 1 behind the intake manifold(forgot what its called). As for the cat, I thought i heard awhile back that if you don’t have a heat shield and you park over grass or something then it will be extremely hot and that may provide most of u with an explanation because i know lots of people take there heat shield off because it likes to rattle. If your getting a map sensor code that would explain why you smell so much gas because its exactly what was wrong with my car because i had one of the wires to the ecu unplugged cuz some idiot from this site told me to(shows my brains right, lol). Found out when i had the voltage tested on the wire to find out if it was the same as the one going to the map sensor and it was, so i knew that was the cause cuz the wire goes from the map sensor to the ecu. As for vtec i’m sure your really not experiencing it at this point, but if you have a CEL then you aren’t able to get vtec period.

I hope this helps

Exhaust Gas Temperature (EGT) pwns you.

first of all egt’s are related to ignition timing, and a/f ratios. You said your fuel return line is dumping into your coolant resevoir? wtf? why would you do that? anyway hook the damn line back up because your probably not achieving proper fuel pressure and the car is running lean and jacking up your egt’s and making the cat glow. and also how do you drive? if you sit at 7K rpm all day long of course shits going to glow, and eventually blowup.

and one more word of advice, stop trying to fix your car, find some people who know what there doing and pay them to fix your car.

maybe the cat if plugged?, when its cooled down, knock on it and if its hollow its somthing else…if its solid its plugged. i had the same problem…

2 ways a cat glows red…either it is clogged or your car is running too rich. The running rich part could be because of a bad fuel pressure reg or it is out of time and combustion is still happening in the exhaust stroke.

guy above is 100 percent correct but man you guys with those problems really should do some reading of service manuals before you work on your cars before you mess them up. your cats probably fried now and if you have smog it wont pass. and if you replace you probably would want a 3 way cat cuz our hondas produce lots of nox. and you dont need that 2nd o2 sensor is only for obd2 cars its a cat monitor.